[cros_colors] Add a PRESUBMIT to find removed colors.

This CL adds a PRESUBMIT to ui/chromeos/colors that greps through the
codebase for generated CSS variables for any removed colors.

Bug: 1018654
Change-Id: I011a035a6d8c28e913ebdc31f8b3f2ea88e38952
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2315370
Commit-Queue: calamity <calamity@chromium.org>
Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Jiewei Qian  <qjw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792584}

tools/style_variable_generator/PRESUBMIT.py

@@ -7,14 +7,33 @@ See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
-WHITELIST = [r'.+_test.py$']
+TEST_ALLOWLIST = [r'.+_test.py$']
+STYLE_VAR_GEN_INPUTS = [
+    r'^tools[\\\/]style_variable_generator[\\\/].+\.json5$'
+]
+
+
+def _CommonChecks(input_api, output_api):
+    results = input_api.canned_checks.RunUnitTestsInDirectory(
+        input_api, output_api, '.', allowlist=TEST_ALLOWLIST)
+    try:
+        import sys
+        old_sys_path = sys.path[:]
+        sys.path += [
+            input_api.os_path.join(input_api.change.RepositoryRoot(), 'tools')
+        ]
+        import style_variable_generator.presubmit_support
+        results += (
+            style_variable_generator.presubmit_support.FindDeletedCSSVariables(
+                input_api, output_api, STYLE_VAR_GEN_INPUTS))
+    finally:
+        sys.path = old_sys_path
+    return results
 
 
 def CheckChangeOnUpload(input_api, output_api):
-    return input_api.canned_checks.RunUnitTestsInDirectory(
-        input_api, output_api, '.', whitelist=WHITELIST)
+    return _CommonChecks(input_api, output_api)
 
 
 def CheckChangeOnCommit(input_api, output_api):
-    return input_api.canned_checks.RunUnitTestsInDirectory(
-        input_api, output_api, '.', whitelist=WHITELIST)
+    return _CommonChecks(input_api, output_api)

tools/style_variable_generator/base_generator.py

@@ -73,6 +73,10 @@ class BaseGenerator:
     globals to render their output.
     '''
 
+    @staticmethod
+    def GetName():
+        return None
+
     def __init__(self):
         self.out_file_path = None
         # A map of input filepaths to their context object.
@@ -139,6 +143,8 @@ class BaseGenerator:
         # rolled.
         data = json5.loads(json_string,
                            object_pairs_hook=collections.OrderedDict)
+        if generator_name is None:
+            generator_name = self.GetName()
         generator_context = data.get('options', {}).get(generator_name, None)
         self.in_file_to_context[in_file] = generator_context
 

tools/style_variable_generator/find_invalid_css_variables.py

@@ -9,21 +9,13 @@ import os
 import subprocess
 import sys
 from css_generator import CSSStyleGenerator
-
-
-def RunGit(command):
-    """Run a git subcommand, returning its output."""
-    command = ['git'] + command
-    proc = subprocess.Popen(command, stdout=subprocess.PIPE)
-    out = proc.communicate()[0].strip()
-    return out
+from presubmit_support import RunGit
 
 
 # TODO(calamity): extend this checker to find unused C++ variables
 def FindInvalidCSSVariables(json_string, input_file, git_runner=RunGit):
     style_generator = CSSStyleGenerator()
-    style_generator.AddJSONToModel(json_string, style_generator.GetName(),
-                                   input_file)
+    style_generator.AddJSONToModel(json_string, in_file=input_file)
 
     context = style_generator.in_file_to_context[input_file]
     if (not context or 'prefix' not in context):

tools/style_variable_generator/presubmit_support.py

+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import argparse
+import os
+import subprocess
+import sys
+from css_generator import CSSStyleGenerator
+
+
+def BuildGrepQuery(deleted_names):
+    # Query is built as \--var-1|--var-2|... The first backslash is necessary to
+    # prevent --var-1 from being read as an argument. The pipes make a big OR
+    # query.
+    return '\\' + '|'.join(deleted_names)
+
+
+def RunGit(command):
+    """Run a git subcommand, returning its output."""
+    command = ['git'] + command
+    proc = subprocess.Popen(command, stdout=subprocess.PIPE)
+    out = proc.communicate()[0].strip()
+    return out
+
+
+def FindDeletedCSSVariables(input_api, output_api, input_file_filter):
+    files = input_api.AffectedFiles(
+        file_filter=lambda f: input_api.FilterSourceFile(
+            f, files_to_check=input_file_filter))
+
+    def get_css_var_names_for_contents(contents_function):
+        style_generator = CSSStyleGenerator()
+        for f in files:
+            style_generator.AddJSONToModel('\n'.join(contents_function(f)),
+                                           in_file=f.LocalPath())
+        return style_generator.GetCSSVarNames()
+
+    old_names = get_css_var_names_for_contents(lambda f: f.OldContents())
+    new_names = get_css_var_names_for_contents(lambda f: f.NewContents())
+
+    deleted_names = old_names.difference(new_names)
+    if not deleted_names:
+        return []
+
+    # Use --full-name and -n for formatting, -E for extended regexp, and :/
+    # as pathspec for grepping across entire repository (assumes git > 1.9.1)
+    problems = RunGit([
+        'grep', '--full-name', '-En',
+        BuildGrepQuery(deleted_names), '--', ':/'
+    ]).splitlines()
+
+    if not problems:
+        return []
+
+    return [
+        output_api.PresubmitPromptWarning(
+            'style_variable_generator variables were deleted but usages of ' +
+            'generated CSS variables were found in the codebase:',
+            items=problems)
+    ]

ui/chromeos/colors/PRESUBMIT.py

+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+STYLE_VAR_GEN_INPUTS = [r'^ui[\\/]chromeos[\\/]colors[\\/].+\.json5$']
+
+
+def _CommonChecks(input_api, output_api):
+    results = []
+    try:
+        import sys
+        old_sys_path = sys.path[:]
+        sys.path += [
+            input_api.os_path.join(input_api.change.RepositoryRoot(), 'tools')
+        ]
+        import style_variable_generator.presubmit_support
+        results += (
+            style_variable_generator.presubmit_support.FindDeletedCSSVariables(
+                input_api, output_api, STYLE_VAR_GEN_INPUTS))
+    finally:
+        sys.path = old_sys_path
+    return results
+
+
+def CheckChangeOnUpload(input_api, output_api):
+    return _CommonChecks(input_api, output_api)
+
+
+def CheckChangeOnCommit(input_api, output_api):
+    return _CommonChecks(input_api, output_api)